The invention concerns methods and apparatus for the production of a plastic coated cardboard can.
German Document DE-30 23 835 shows and describes a can comprising a plastic coated cardboard cylinder with an inner aluminum layer and defining, in the finished state, a sleeve to each of the two open ends of which a frontal or end wall is applied. The known machines for the production of such cans are laid out so that the can is produced initially in the form of a cup having a closed end and an open end into which the filler goods, such as beverages, are inserted. The initial production apparatus therefore comprises only one station for the insertion of a first end wall at the closed end. After filling, the second end wall is inserted in another apparatus. A type of induction welding is used to join the seams, both in case of the first and the second end walls, which requires the use of the aluminum layer. When filled cans are prepared in this manner, it is difficult to insert and connect the second end wall (which may contain a hole closed by tear-off tab for use as a discharging opening for the insertion of a straw), because of interference created by the filler material already in the can, especially as regards wetting the area of the weld seams. That is, a filler material in the form of a liquid produces a humid environment which can penetrate into the area where a seam is to be formed between the end wall and the can sleeve, thereby complicating that welding procedure by making it difficult to attain a proper sealing temperature, etc.
It is, therefore, an object of the invention to provide an apparatus of the afore-mentioned type so that these disadvantages are avoided. In particular, it should be possible in a simple manner to prevent the penetration of humidity, in the case of liquid filler materials, into the area of the can seams prior to sealing. Another object is to provide a method of conveniently making and filling a can.